I really liked this, solid ratings all round. My biggest gameplay criticism is that failing should be "restart the level" not "restart the game" in a game of this length. The most major bug was that all the captions for the event seemed to show the one for the prehistoric land bridge, which was a pity.
On the history side, some of the presentation of things could have been made a bit fuzzier, making it clearer in earlier periods that the events were "circa" and indeed were in many cases really processes, rather than the slightly old-school "this happened in this year" way of presenting things.. I really liked the red herring events and I particularly liked the half-plausible sounding ones (like "Romans invading Ireland"), but wasn't sure they did much game-wise (unless there was some penalty for drag-and-dropping them that I didn't find).
Anyway, generally really liked it, good job!